Pollock and pollack fish are not the same thing! They're both quite similar to cod, and can be used as a replacement for cod in most recipes.

Does pollock fish taste like cod?

Alaskan Pollock Flavor Scale

Alaskan Pollock have a mild, delicate taste with white flesh, large flakes, a slightly coarse texture and a low oil content. They have a similar but somewhat milder flavor as haddock or cod.

What is a good substitute for cod?

Flavor/Texture: Although cod has a delicate, flaky texture, it's also resiliently meaty and can hold up to just about any cooking method. Substitutes: If you can't find Pacific cod, Atlantic cod or true cod, you might consider swapping in lingcod, sole, haddock or pollock.